Two types of magnetic biological effects: individual and batch effects

Frequency distributions of the magnetic effects values have been calculated based on the results of about 120 thousand single trials during psychophysical testing of 40 people under normal conditions and exposure to the hundredfold weakened geomagnetic field. Two types of such distributions were shown to be attributed to a) the individual reactions to the change of a magnetic field and b) the batch magnetic effect on the set of the individual reactions. The methodological consequences significant for detecting magnetic biological phenomena and studying their nature are discussed.     

Magnetic field effects on coenzyme B12-dependent enzymes: Validation of ethanolamine ammonia lyase results and extension to human methylmalonyl CoA mutase

Enzymes with radical-pair intermediates have been considered as a likely target for purported magnetic field effects in humans. The bacterial enzyme ethanolamine ammonia lyase and the human enzyme methylmalonyl-CoA mutase catalyze coenzyme B₁₂-dependent rearrangement reactions. A common step in the mechanism of these two enzymes is postulated to be homolysis of the cobalt-carbon bond of the cofactor to generate a spin-correlated radical pair consisting of the 5′-deoxyadenosyl radical and cob(II)alamin [Ado^· Cbl(II)]. Thus, the reactions catalyzed by these enzymes are expected to be sensitive to an applied magnetic field according to the same principles that control radical pair chemical reactions. The magnetic field effect on ethanolamine ammonia lyase reported previously has been corroborated independently in one of the authors' laboratory. However, neither the human nor the bacterial mutase from Propionibacterium shermanii exhibits a magnetic field effect that could be greater than about 15%, considering the error limit imposed by the uncertainty of the coupled assay. Our studies suggest that putative magnetic field effects on physiological processes are not likely to be mediated by methylmalonyl-CoA mutase. Bioelectromagnetics 18:506–513, 1997. © 1997 Wiley-Liss, Inc.     

Application of the radical pair mechanism to free radicals in organized systems: Can the effects of 60 Hz be predicted from studies under static fields?

The influence of 60-Hz magnetic fields on free radical reactions can be quantitatively predicted from the knowledge of the effect of static fields on free radical behavior. Studies of radical reactions in micellar systems show that the behavior under a 60-Hz field is identical to that under a static field at any given point in time. © 1994 Wiley-Liss, Inc.     

Magnetic and other non-visual orientation mechanisms in some cave and surface urodeles

Animals adapted to light-deprived habitats might have improved non-visual sensory systems. Specimens of several cave-dwelling species of urodeles spontaneously and persistently align to natural or artificially-modified permanent magnetic fields. Video observations under dim infrared illumination revealed an obvious individual preference for one particular magnetic direction in every animal tested. Therefore, animals changed alignments predictably when the horizontal magnetic field vector (compass direction) was artificially reversed or deviated. When the vertical vector was compensated, individuals aligned axially. With the vertical vector reversed (inclination upward), either axial alignment was still typical, or the individuals behaved as with the horizontal vector reversed. However, reactions as to the natural field occurred as well. The findings suggest a receptor mechanism that needs both horizontal and vertical magnetic cues, but it is still an open question how and where the physical and physiological mechanisms of magnetic transduction and reception are realized. The visual system is likely not necessary because Proteus is ontogenetically deprived of eyesight, and the other species were blindfolded due to the faint infrared illumination. The results therefore tend to favor those putative receptor mechanisms, assumed to work by means of magnetite nano-elements. In sum, the ability to align within the geomagnetic field may be considered a prerequisite for magnetic orientation and is, among other sensory improvements, judged to be highly relevant as an important sensorial and ecological adaptation to light-deprived habitats.     

Magnetic field perturbations as a tool for controlling enzyme-regulated and oscillatory biochemical reactions

The feasibility of magnetic field perturbations as a tool for controlling enzyme-regulated and oscillatory biochemical reactions is studied. Our approach is based on recent experimental results that revealed magnetic field effects on the in vitro activity of enzyme systems in accordance with the radical pair mechanism. A minimum model consisting of two coupled enzyme-regulated reactions is discussed that combines, in a self-consistent manner, magnetic field-sensitive enzyme kinetics with non-linear dynamical principles. Furthermore, a simple detector mechanism is described that is capable of responding to an oscillatory input. Results reveal that moderate-strength magnetic fields (B=1-100 mT) may effectively alter the dynamics of the system. In particular, a response behavior is observed that depends on: (1) the combination of static and time-varying magnetic fields; (2) the field amplitude; and (3) the field frequency in a non-linear fashion. The specific response behavior is critically determined by the biochemical boundary conditions as defined by the kinetic properties of the system. We propose an experimental implementation of the results based on the oscillatory peroxidase-oxidase reaction controlled by the enzyme horseradish peroxidase.     

Ring-current effects in the nmr of nucleic acids: A graphical approach

The spatial dependence of the ring-current magnetic anisotropy of nucleic acid bases is presented in a series of graphs in cylindrical coordinates. The curves may be used to calculate the ring-current shift at a point in a cylinder of radius 10Å extending 8 Å above and below each ring of the base. These distance effects are found to influence considerably the predicted chemical shifts of nucleic acid protons, particularly in RNA duplexes. The contribution of polarization (electric field) effects and the diamagnetic anisotropy of individual atoms (local Δ_χ) are briefly discussed.     

Avian orientation: effects of cue-conflict experiments with young migratory songbirds in the high Arctic

The migratory orientation of juvenile white-crowned sparrows, Zonotrichia leucophrys gambelli, was investigated by orientation cage experiments in manipulated magnetic fields performed during the evening twilight period in northwestern Canada in autumn. We did the experiments under natural clear skies in three magnetic treatments: (1) in the local geomagnetic field; (2) in a deflected magnetic field (mN shifted −90°); and (3) after exposure to a deflected magnetic field (mN −90°) for 1 h before the cage experiment performed in the local geomagnetic field at dusk. Subjects showed a mean orientation towards geographical east in the local geomagnetic field, north of the expected migratory direction towards southeast. The sparrows responded consistently to the shifted magnetic field, demonstrating the use of a magnetic compass during their first autumn migration. Birds exposed to a cue conflict for 1 h on the same day before the experiment, and tested in the local geomagnetic field at sunset, showed the same northerly orientation as birds exposed to a shifted magnetic field during the experiment. This result indicates that information transfer occurred between magnetic and celestial cues. Thus, the birds' orientation shifted relative to available sunset and geomagnetic cues during the experimental hour. The mean orientation of birds exposed to deflected magnetic fields prior to and during testing was recorded up to two more times in the local geomagnetic field under natural clear and overcast skies before release, resulting in scattered mean orientations.Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved .     

Photoelectric effects in bone

The lifetime of photogenerated carriers (using pulsating light in the infrared region) and the effect of magnetic field on photoconductivity in bone and its two major components have been estimated. Lifetime was found to be in the order of microseconds. An estimation of diffusion length with the knowledge of drift mobility yields the value 1̃0^?5cm. Photoconductivity (infrared light) was examined in the region of very low electric field and was found to be enhanced due to the magnetic field. A possible mechanism for carrier generation and decay is suggested.     

Easily handling penicillin G acylase magnetic cross-linked enzymes aggregates: Catalytic and morphological studies

Biomolecules labeled with superparamagnetic nanoparticles can be selectively removed from complex reaction mixtures using an external magnetic field. Amino-functionalized superparamagnetic iron oxide nanoparticles (amino-SPION) were co-aggregated with penicillin G acylase and then cross-linked, generating magnetic cross-linked enzymes aggregates (M-CLEAs) that were quickly and efficiently recovered from the reaction medium by applying an external magnetic field. M-CLEAs and cross-linked enzymes aggregates (CLEAs) prepared under the same reaction conditions were characterized and compared. The best recovered activities were obtained for M-CLEAs prepared using polyethylene glycol 600 as precipitant and the most stable M-CLEA were obtained using tert-butanol. Successive penicillin G hydrolysis reactions were carried out using the same M-CLEA in a 50 mL reactor (3 reaction cycles), after the reactions the derivate was magnetically recovered without loss of activity demonstrating a total magnetic recovery. Line-scan energy dispersive X-ray spectroscopy showed that the amino-SPIONs were homogeneously dispersed within the structure of the M-CLEA.     

On the mechanism of magnetic field effects in bacterial photosynthesis.

The recently discovered magnetic field effects in bacterial photosynthesis are discussed by solving a simple model exactly. Analytic expressions are given that permit one to study the influence of the rates of the primary electron transfer reactions and the exchange interaction on the yield of excited triplet states.     

Geomagnetic effects on a circadian difference in reaction times in earthworms

Summary The effect of geomagnetic force on the light-withdrawal reflex of earthworms, Lumbricus terrestris, L., was investigated during the autumn of 1968. The reactions of worms kept in the earth's magnetic field were timed beginning at 12:00 and at 20:00, E.S.T. on each of 63 days; the same was done for worms maintained in a field whose intensity was essentially zero. The worms in the earth's field withdrew from light significantly faster at night then at midday. No significant difference between the mean reaction times at 12:00 and those of the evening were found for the animals which lived and were tested in the greatly reduced magnetic field. Therefore, geomagnetism does have some effect on the circadian difference in reaction rates in this species.

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Zusammenfassung Die Wirkung des erdmagnetisohen Feldes auf die Lichtreaktion von Lumbricus terrestris wurde untersucht (Herbst 1968). Als Test wurde die Reaktion auf einen Lichtreiz verwendet. Ein Teil der Würmer wurde im natürlichen erdmagnetisehen Feld, ein anderer Teil in einem auf Null kompensierten Feld gehalten. Die Reaktionszeiten auf den Lichtreiz wurden bei beiden Gruppen um 12.00 und um 20.00 Uhr gemessen. Die Reaktionszeiten im natürlichen erdmagnetischen Feld waren abends signifikant (p=0,005) kürzer (7,2 sec) als mittags (8,9 sec). Im Feld, das nahezu auf Null kompensiert war, waren die Reaktionszeiten abends und mittags gleich (8,8 bzw. 8,7 sec). Der Erdmagnetismus hat also einen Einfluß auf die circadiane Differenz der Reaktionszeiten bei Lumbricus.

     

Effect of a magnetic field and copper upon activity of hydrolytic enzymes in roach (Rutilus rutilus) underyearlings

Remote effects of separate and combined exposure to copper (0.001 mg/L and 0.01 mg/L) and a low-frequency magnetic field during early embryogenesis in roach (Rutilus rutilus) underyearlings were studied. The study revealed that exposures lead to changes in the linear and weight parameters, activity of glycosidases, and kinetic characteristics of carbohydrates hydrolysis in the fish intestine. Copper decreases the activity of glycosidases and modifies the effect of a magnetic field. The exposure-induced decrease in the value of the seeming Michaelis constant of carbohydrate hydrolysis indicates the increase in the enzyme-substrate affinity. This phenomenon may be attributed to the adaptive reactions in response to negative effects of copper and a magnetic field during early ontogenesis in roach.     

Behavioural evidence that magnetic field effects in the land snail,Cepaea nemoralis,might not depend on magnetite or induced electric currents

Although extremely low frequency (ELF) magnetic fields (<300 Hz) appear to exert a variety of biological effects, the magnetic field sensing/transduction mechanism(s) remains to be established. Here, using the inhibitory effects of magnetic fields on endogenous opioid peptide-mediated “analgaesic” response of the land snail. Cepaea nemoralis, we addressed the mechanism(s) of action of ELF magnetic fields. Indirect mechanisms involving both induced electric fields and direct magnetic field detection mechanisms (e.g., magnetite, parametric resonance) were evaluated. Snails were exposed to a static magnetic field (B_DC=78±1 μT) and to a 60 Hz magnetic field (B_AC=299±1 μT peak) with the angle between the static and 60 Hz magnetic fields varied in eight steps between 0° and 90°. At 0° and 90°, the magnetic field reduced opioid-induced analgaesia by approximately 20%, and this inhibition was increased to a maximum of 50% when the angle was between 50° and 70°. Because B_AC was fixed in amplitude, direction, and frequency, any induced electric currents would be constant independent of the B_AC/B_DC angle. Also, an energy transduction mechanism involving magnetite should show greatest sensitivity at 90°. Therefore, the energy transduction mechanism probably does not involve induced electric currents or magnetite. Rather, our results suggest a direct magnetic field detection mechanism consistent with the parametric resonance model proposed by Lednev. © 1996 Wiley-Liss, Inc.     

Effects of magnetic field exposure on fertilization success in rainbow trout,Salmo gairdneri

The sensitivity of trout ova and sperm to 1-T magnetic fields was investigated. It was determined that (1) overall test results combining seven independent Z-statistics demonstrated a significant (α < 0.0001) enhancement of fertilization when ova alone were exposed to the magnetic field prior to fertilization; (2) similarly, overall test results combining Z-statistics from eight independent experiments indicated a significant (α < 0.0004) enhancement when sperm alone were exposed; and (3) statistical analysis of nine independent experiments confirmed enhanced fertilization (α < 0.0001) when both ova and sperm were exposed to the magnetic field prior to fertilization. Although these data indicated that both ova and sperm were sensitive to magnetic fields, simultaneous exposure of both gametes did not have a greater total effect on fertilization rate than the sum of their individual effects.     

Light-dependent and -independent behavioral effects of extremely low frequency magnetic fields in a land snail are consistent with a parametric resonance mechanism

Exposure to extremely low frequency (ELF) magnetic fields has been shown to attenuate endogenous opioid peptide mediated antinociception or “analgaesia” in the terrestrial pulmonate snail, Cepaea nemoralis. Here we examine the roles of light in determining this effect and address the mechanisms associated with mediating the effects of the ELF magnetic fields in both the presence and absence of light. Specifically, we consider whether the magnetic field effects involve an indirect induced electric current mechanism or a direct effect such as a parametric resonance mechanism (PRM). We exposed snails in both the presence and absence of light at three different frequencies (30, 60, and 120 Hz) with static field values (B_DC) and ELF magnetic field amplitude (peak) and direction (B_AC) set according to the predictions of the PRM for Ca²⁺. Analgaesia was induced in snails by injecting them with an enkephalinase inhibitor, which augments endogenous opioid (enkephalin) activity. We found that the magnetic field exposure reduced this opioid-induced analgaesia significantly more if the exposure occurred in the presence rather than the absence of light. However, the percentage reduction in analgaesia in both the presence and absence of light was not dependent on the ELF frequency. This finding suggests that in both the presence and the absence of light the effect of the ELF magnetic field was mediated by a direct magnetic field detection mechanism such as the PRM rather than an induced current mechanism. Bioelectromagnetics 18:284–291, 1997. © 1997 Wiley-Liss, Inc.     

Vegetative reactions of dolphins to a change in the permanent magnetic field]

Vegetative responses of dolphin to changes in permanent magnetic field were studied. Electrocardiograms, cutaneogalvanic reactions, and respiration were registered. These parameters were compared with the functional behavior of dolphin: motion, sharp frequent expirations, and acoustic activity. Functional responses to permanent magnetic fields of 32; 108 and 168 microT were registered in 79.2, 63.3 and 52.9% of presentations, respectively. The frequency of responses in control at a power of geomagnetic field of 48.5 microT was 32.7%. Five latent periods were observed in the response of dolphin to changes in magnetic field (72% of responses). It is shown that dolphins have a high responsiveness to changes in permanent magnetic field "magnetic sense").     

Electromagnetic induced kinetic effects on charged substrates in localized enzyme systems.

An analytical expression for the rate efficiency factor of planar localized enzyme systems is derived. The derivation takes into account the isothermal kinetic effect under the externally imposed perturbation of combined electrostatic and high frequency time-varying fields. The contribution of each individual field to the enzyme reaction is examined through the basic mechanism in which charged substrates interact with the specific perturbing field. The interaction mechanisms for the electrostatic and for the time-varying fields are found to be different. This difference regulates the different manners in which enzymatic reaction rates are altered. Enzymatic reactions under electrostatic perturbation can be retarded or enhanced depending on the field polarization. At sufficiently high field intensities the reaction rate may approach zero or approach a maximum value equal to the turnover number of the enzyme. Time-varying field perturbations, on the other hand, always enhance the enzymatic reactions if bunching effects are negligible. At sufficiently high field intensities, the reaction may approach a value equal to that of the free enzyme system. Several typical numerical examples on pure eletrostatic field perturbations, pure time-varying field perturbations, and combined field perturbations are also presented.     

The Influence of Low Magnetic Fields and Magnesium Isotopes on <Emphasis Type="Italic">E. coli</Emphasis> Bacteria

The combined effects of external low static magnetic fields at 0–22 mT and magnesium isotopes on the growth and development of E. coli bacteria has been studied. The magnetic field and ²⁵Mg magnetic isotope effects were obtained in two ranges: 0.8–3.0 and 8–13 mT. The experimental values of the growth rate, the number of CFUs and the ATP pool of bacteria enriched in magnetic magnesium isotope ²⁵Mg (nuclear spin, I = 5/2) in the range of 0.8–3.0 mT are significantly higher compared to bacteria enriched in nonmagnetic isotopes ²⁴Mg, ²⁶Mg, or natural magnesium. The increase in the growth rate, colony-forming ability, and intracellular ATP concentration in bacteria in all groups cultivated under exposure to an external static magnetic field in the range of 0.8 to 3.0 mT confirms the existence of magnetosensitive stages of enzymatic reactions that proceed via the ion-radical mechanism. The combined influence of the magnetic field in the range of 8 to 13 mT and the magnesium magnetic isotope ²⁵Mg on the colony forming ability of E. coli bacteria is associated with processes that are responsible for cell division. The above-mentioned effects of bacterial magnetosensitivity (to magnetic fields and magnetic isotopes) are in good agreement with theoretical predictions of the theory of spin-dependent enzymatic reactions.     

Magnetic field effects on activity and ageing in honeybees

Artificial magnetic fields (MF) influence physiological processes in bees.